Thermal jacket on rocking autoclave



1964 E. WALLSTROM ETAL 3,155,155

THERMAL JACKET 0N ROCKING AUTOCLAVE Filed Feb. 20. 1962 2 Sheets-Sheet 2 5 i 23 34/ I! '30 I. 22 ESKEL figf r ii R/CHARD LAPHAM GILBERT v BY 24 WW nj;

ATTORNEY United States Patent C) TIERMAL JACKET N ROCKING AUTOCLAVE Eskel Wallstrom, Greenwich, and Richard Lapharn Gilhert, In, Old Greenwich, Conn, assignors to American Cyanarnid Company, New York, N.Y., a corporation of Maine Filed Feb. 20, 1962, Ser. No. 174,491 1 Claim. (Cl. 165-12) This invention relates to a thermal jacket on an autoclave, more particularly a rocking autoclave, which jacket has provisions for adding or removing heat and changing the rate rapidly as may be required by an unexpected exotherm or as may be required by a temperature program.

Rocking autoclaves are conventionally used in high temperature and high pressure procedures. An autoclave, frequently with the length several times the diameter, is rocked to insure agitation of the contents. Most such autoclaves are designed to have a gas-tight closure and very strong walls to stand pressures of from several hundred pounds per square inch to many thousands of pounds per square inch. Usually such autoclaves have provisions for a temperature measurement means, frequently a thermocouple, although thermistors, resistance thermometers or other types of temperature measuring devices may be used; and usually the autoclave has some form of a pressure measuring device which may be a gauge or transducer. Frequently there is means for introducing a gas under pressure as, for example, where the reaction involves the addition of, or reaction with hydrogen, or other gas, or where nitrogen or other inert gas is used to maintain pressure.

Because corrosion is frequently a problem, and the autoclave must be kept sealed, the autoclaves are comparatively expensive.

Heating jackets have been used to heat the autoclave and integral passages for heating fluids have been formed in the autoclave. In general, if the heating means are integral with the autoclave, the cost is increased and the flexibility of usage is decreased. If a completely separate heating means is used, the rate of heat transfer may be unduly low.

By this invention, it has been found that a jacket is formed for a high pressure autoclave of a material having a high thermal conductivity in which there are passages or chambers for electrical resistance heating elements and also separate passages for a coolant. Preferably both the heating elements and the coolant passages are within a single jacket so that the resistance to heat flow is a minimum, and permits either the release of heat to or absorption of heat from the autoclave. Some reactions and experiments unexpectedly generate heat, and unless there is provision for a rapid and eflicient cooling, the temperature of the contents of the autoclave may rise to such a point that the experiment is useless. A rapid increase in rate of heat removal is essential.

The above and other advantages of the present invention are more readily understood from one embodiment thereof which is shown in the accompanying drawings in which:

FIGURE 1 is a pictorial view in half section, and partly broken away, of the novel autoclave jacket, assembled with an autoclave.

FIGURE 2 is a longitudinal sectional View of the thermal jacket along section lines 2-2 of FIGURE 3, part of the section being a rotated section.

FIGURE 3 is a cross-section, at right angles to the longitudinal axis of the jacket, principally along plane 33 of FIGURE 2, but with one part broken away to show the lower ends of the cooling passages.

3,155,155 Patented Nov. 3, 1964 As shown in FIGURE 1, an autoclave body 11 is provided with an autoclave closure 12, which is attached to the body by conventional means. Both are of corrosion-resistant material such as stainless steel and may be platinum lined for extreme corrosion resistance.

Through the closure pass leads to a thermocouple 13 which may be either in a special thermocouple well, or connected through electrically insulating bushings to the thermocouple in the interior of the autoclave. Other temperature measuring means may be used. A pressure transducer 14 connects to the interior of the autoclave. A gas feed line 15 passes through the closure to permit the addition of an inert or reactant gas at any desired pressure.

Surrounding the autoclave is the thermal jacket 16; which is preferably of a material having high thermal conductivity such as aluminum, or copper. The thermal jacket is of such size as to fit closely about the outside of the autoclave to increase heat transfer. At the open end of the thermal jacket is a closure enlargement 17 in which the interior of the thermal jacket is enlarged to provide clearance for the autoclave closure. While interchangeable for autoclaves of the same size and shape, different sizes of thermal jackets are preferred for autoclaves of different sizes so as to give a good fit with each.

From the bottom end 18 of the thermal jacket 16 there extends, parallel to the axis of the jacket, and into the jacket, a group of heating chambers 19 for electrical heating elements 20. The chambers preferably extend nearly the full length of the main body of the jacket so that they are about as long as the autoclave body and preferably the electrical heating elements are enclosed cartridge-type heaters which are themselves electrically insulated so that their external surface supplies heat but is free from shock hazards. The chambers conveniently are round for round heating elements, but other sizes and shapes may be used. The electrical leads 21 from the electrical heating elements extend into a lead shield 22 which is appropriately fastened to the outside of the thermal jacket as, for example, by screws 23. A lead shield cover 24 cooperates with the lead shield to form a terminal box 25 from which the external leads 26 extend to an appropriate power source 36, later described.

Also in the thermal jacket, and parallel to the axis thereof, are coolant passages 27. Conveniently, the coolant passages are drilled in the thermal jacket, parallel to its axis, in adjacent pairs, between each set of heating chambers 19. At the top end of the coolant passages 27 a blind hole 28 is drilled into the ends of the adjacent coolant passages to provide a connection between them.

The blind hole 28 is tapped and then closed with a blind hole plug 29. A conventional pipe tap may be used and the plugs need only be removed if the coolant passages become clogged and must be cleaned. The bottom end of each coolant passage is tapped and a coolant plug 30 inserted therein. Conveniently, but not necessarily, both the blind hole plugs and the coolant plugs are fitted for an Allen or hexagonal wrench and the plugs are of such length that the outer ends of the plugs are substantially contiguous with the adjacent jacket surfaces. Adjacent to the coolant plug end of the coolant passages is a coolant connection 31, which is a drilled and tapped hole extended from the outer surface of the thermal jacket into the coolant passages so that a coolant can fiow into one passage and out of the adjacent passage, thus giving U-shaped passages in the thermal jacket which extend substantially the entire length of the autoclave body.

A tapped retaining screw hole 32 is provided near the top of the thermal jacket for a retaining screw 33 to hold the autoclave in position in the thermal jacket.

As shown in FIGURE 2, a jacket bottom 34 closes the lower end of the jacket and protects the electrical leads in the thermal box from damage through the opening for the autoclave in the thermal jacket.

In use the thermocouple and pressure transducer feed a signal to a programmer 35, which programmer in turn controls the flow of electrical current from a power source 36 through a suitable controller 37, such as a relay to the external leads 26. The flow of a coolant from an external source is controlled by a coolant valve 38.

Operation In use electric power is supplied to heat the thermal jacket and warm up the thermal jacket and the enclosed autoclave. The rate of heating can be controlled by a programmer 35 automatically or conveniently can be controlled by an operator who watches the temperature and pressure and takes appropriate action to control the rate of power supply such that a desired temperature rise rate is obtained. When either the temperature or the pressure rises faster than desired, a coolant is supplied through the coolant valve 38 to reduce the temperature of the jacket and cut off the supply of heat to the autoclave and, if necessary, remove heat from the autoclave to keep the temperature and/or pressure at desired values. The coolant may be water, either cold or hot, or air or steam, depending upon the temperature ranges and rates of heat removal desired. A programmer is convenient for automatically controlling the temperature cycles over any desired period, from a matter of a few minutes to many days. For a simpler installation gauges may be used for temperature and pressure, which permit the operator to make his own selection of the rate of supply of either electrical power or coolant to maintain the temperature and/or pressure as desired for a particular experiment.

Obviously, automatic recorders may be used to give a transient or permanent indication of temperature, pressure, rate of heating, and rate of cooling, or as many of these factors as may be desired. The present jacket systern is extremely flexible and may be used under a wide variety of conditions, controlled principally by the requirements of the particular research program.

A jacket thermocouple Well 39 is provided in the thermal jacket. The temperature of the jacket is thus measured. The difierence of the jacket temperature and the autoclave temperature is determined, which is the temperature difierential causing heat to flow. For inert reactants, the thermal capacity is known, or can be determined, so that the rate of temperature rise can be found as a function of thermal capacity and rate of heat flow. Any deviation from this rate, is due to the heat of reaction of the autoclave contents, which can thus be calculated as a function of temperature, An exotherm, or change in rates of reaction, or a phase transformation involving heat eifects, can be more rapidly and sensitively measured than by the rate of temperature rise alone. 'A change in temperature dilference between the jacket and the autoclave can be programmed by machine or by the operator for control of the rate of addition of a subtraction of heat.

Having described one modification thereof, the scope of the present invention is set forth in the following claim.

We claim:

A temperature controlled autoclave for high-pressure reactions having (a) a cylindrical autoclave body capable of withstanding high pressures,

(b) a pressure tight closure therefor,

(c) a temperature sensing means to sense temperature within the autoclave, and in combination with the autoclave body and readily separable therefrom,

(d) a cylindrical thermal jacket of material having a high thermal conductivity, having a smooth unbroken inner cylindrical face which fits closely in concentric heat exchanging relationship with the entire cylindrical outer surface of the autoclave body, said jacket having therein, and parallel to the longitudinal axis thereof,

(e) a plurality of heating chambers for electrical heating elements,

(f) electrical heating elements in said chambers, and

totally enclosed by said chambers except for electrical leads, said jacket also having therein, and spaced between such chambers,

(g) a plurality of U-shaped cooling passages formed by parallel cylindrical bores, parallel to the longitudinal axis of the jacket, including means at one end of each of the bores for interconnecting adjacent bores serially,

(h) means at the opposed ends of the interconnected bores to supply coolant to and receive coolant from said bores, and said cooling passages and heating chambers symmetrically and completely surrounding the autoclave body,

(1') a source of electricity,

(i) means to control the electric current from said source to said heating element,

(k) a coolant supply source,

(1) means to control the coolant flow from said source to and through said cooling passages, and

(m) a programmer, connected to the temperature sensing means, having therein means to selectively control the electric current control means and the coolant flow control means to maintain a desired time and temperature program for the contents of the autoclave, independent of heat generated by re actants within the autoclave.

References Cited by the Examiner UNITED STATES PATENTS CHARLES SUKALO, Primary Examiner, 

